Level 1 character vs level 13 character

[mabriss lethe]

If you are inside it and leave it unlocked, entering it is using a magic item, so he'll lose all his forsaker abilities if he follows you. Feel free to snipe him from the upper floor windows.

I first thought that trapping him in there with nothing but a sustaining spoon would be a wonderful insult, but I actually reread VoP and realized it was a pointless one if he has the Vow or otherwise doesn't need to eat.

EDIT TO ADD:
A most cunning way to win, with a two item combo. it'll take all the character's WBL, but fits the basic criteria. An instant fortress and a Cloak of etherealness. Deploy the fortress. Run inside. Leave the door open. Let him come to you. When he enters, lock him in, use the cloak, and saunter out right through the walls.